The Reactive Engine for Modular Transducers

  • Gérard Huet
  • Benoît Razet
Part of the Lecture Notes in Computer Science book series (LNCS, volume 4060)


This paper explains the design of the second release of the Zen toolkit [5–7]. It presents a notion of reactive engine which simulates finite-state machines represented as shared aums [8]. We show that it yields a modular interpreter for finite state machines described as local transducers. For instance, in the manner of Berry and Sethi, we define a compiler of regular expressions into a scheduler for the reactive engine, chaining through aums labeled with phases — associated with the letters of the regular expression. This gives a modular composition scheme for general finite-state machines.

Many variations of this basic idea may be put to use according to circonstances. The simplest one is when aums are reduced to dictionaries, i.e. to (minimalized) acyclic deterministic automata recognizing finite languages. Then one may proceed to adding supplementary structure to the aum algebra, namely non-determinism, loops, and transduction. Such additional choice points require fitting some additional control to the reactive engine. Further parameters are required for some functionalities. For instance, the local word access stack is handy as an argument to the output routine in the case of transducers. Internal virtual addresses demand the full local state access stack for their interpretation.

A characteristic example is provided, it gives a complete analyser for compound substantives. It is an abstraction from a modular version of the Sanskrit segmenter presented in [9]. This improved segmenter uses a regular relation condition relating the phases of morphology generation, and enforcing the correct geometry of morphemes. Thus we obtain compound nouns from iic*.(noun+iic.ifc), where iic and ifc are the respectively prefix and suffix substantival forms for compound formation.


Regular Expression Input Tape Virtual Address Lexical Category Reactive Engine 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.


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  1. 1.
    Antimirov, V.: Partial derivatives of regular expressions and finite automaton constructions. Theoretical Computer Science 155, 291–319 (1996)MATHCrossRefMathSciNetGoogle Scholar
  2. 2.
    Berry, G., Sethi, R.: From regular expressions to deterministic automata. Theoretical Computer Science 48, 117–126 (1986)MATHCrossRefMathSciNetGoogle Scholar
  3. 3.
    Berstel, J., Pin, J.-E.: Local languages and the Berry-Sethi algorithm. Theoretical Computer Science 155, 439–446 (1996)MATHCrossRefMathSciNetGoogle Scholar
  4. 4.
    Eilenberg, S.: Automata, Languages, and Machines, A. Academic Press, London (1974)MATHGoogle Scholar
  5. 5.
    Huet, G.: The Zen computational linguistics toolkit. Technical report, ESSLLI Course Notes (2002),
  6. 6.
    Huet, G.: The Zen computational linguistics toolkit: Lexicon structures and morphology computations using a modular functional programming language. In: Tutorial, Language Engineering Conference LEC 2002 (2002)Google Scholar
  7. 7.
    Huet, G.: Linear contexts and the sharing functor: Techniques for symbolic computation. In: Kamareddine, F. (ed.) Thirty Five Years of Automating Mathematics, Kluwer, Dordrecht (2003), Google Scholar
  8. 8.
    Huet, G.: Automata mista. In: Dershowitz, N. (ed.) Verification: Theory and Practice. LNCS, vol. 2772, pp. 359–372. Springer, Heidelberg (2004), Google Scholar
  9. 9.
    Huet, G.: A functional toolkit for morphological and phonological processing, application to a Sanskrit tagger. J. Functional Programming 15(4), 573–614 (2005), MATHCrossRefGoogle Scholar
  10. 10.
    Roche, E., Schabes, Y.: Finite-State Language Processing. MIT Press, Cambridge (1997)Google Scholar
  11. 11.
    Sproat, R.: Morphology and Computation. MIT Press, Cambridge (1992)Google Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2006

Authors and Affiliations

  • Gérard Huet
    • 1
  • Benoît Razet
    • 1
  1. 1.INRIA RocquencourtLe Chesnay CedexFrance

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